Composite material with thermoplastic toughened novolac-based epoxy resin matrix

Abstract

Pre-impregnated composite material (prepreg) that can be cured/molded to form aerospace composite parts. The prepreg includes carbon reinforcing fibers and an uncured resin matrix. The resin matrix includes an epoxy component that is a combination of a hydrocarbon epoxy novolac resin and a trifunctional epoxy resin and optionally a tetrafunctional epoxy resin. The resin matrix includes polyethersulfone as a toughening agent and a thermoplastic particle component.

What is claimed is: 
     
       1. A pre-impregnated composite material comprising:
 A) reinforcing fibers comprising carbon fibers; and 
 B) an uncured resin matrix comprising:
 a) an epoxy resin component comprising from 17 to 27 weight percent of a hydrocarbon epoxy novolac resin, based on the total weight of said uncured resin matrix, and from 26 to 36 weight percent of a triglycidyl meta-aminophenol, based on the total weight of said uncured resin matrix; 
 b) 11 to 19 weight percent of a thermoplastic particle component based on the total weight of said uncured resin matrix, said thermoplastic particle component comprises a mixture of a first group of polyamide particles that do not comprise crosslinked polyamide and a second group of polyamide particles that comprise crosslinked polyamide; 
 c) 7 to 12 weight percent of a thermoplastic toughening agent, based on the total weight of said uncured resin matrix, said thermoplastic toughening agent comprising polyethersulfone; and 
 d) 17 to 27 weight percent of a curing agent, based on the total weight of said uncured resin matrix, said curing agent comprising 4,4′-diaminodiphenyl sulphone and/or 3,3′-diaminodiphenyl sulphone. 
 
 
     
     
       2. The pre-impregnated composite material according to  claim 1  wherein the weight ratio of said first group of polyamide particles to said second group of polyamide particles is from 4:1 to 1.5:1. 
     
     
       3. The pre-impregnated composite material according to  claim 2  wherein the weight ratio of said first group of polyamide particles to said second group of polyamide particles is from 3.5:1 to 2.5:1. 
     
     
       4. The pre-impregnated composite material according to  claim 1  wherein said first group of polyamide particles comprises polyamide 11 particles and said second group of particles comprises crosslinked polyamide 12 particles that comprise crosslinked polyamide 12. 
     
     
       5. The pre-impregnated composite material according to  claim 4  wherein the weight ratio of said polyamide 11 particles to said crosslinked polyamide 12 particles is from 4:1 to 1.5:1. 
     
     
       6. The pre-impregnated composite material according to  claim 5  wherein the weight ratio of said polyamide 11 particles to said crosslinked polyamide 12 particles is from 3.5:1 to 2.5:1. 
     
     
       7. The pre-impregnated composite material according to  claim 4  wherein said curing agent comprises 4,4′-diaminodiphenyl sulphone. 
     
     
       8. The pre-impregnated composite material according to  claim 1  wherein said reinforcing fibers comprise a plurality of carbon fiber tows which each comprises from 10,000 to 14,000 carbon filaments wherein the weight per length of each of said carbon tows is from 0.2 to 0.6 grams per meter and wherein the tensile strength of each of said carbon tows is from 750 to 860 kilopounds per square inch and the tensile modulus of each of said carbon tows is from 35 to 45 megapounds per square inch. 
     
     
       9. The pre-impregnated composite material according to  claim 1  wherein said curing agent comprises 4,4′-diaminodiphenyl sulphone. 
     
     
       10. A composite part or structure that has been formed by curing a pre-impregnated composite material according to  claim 1 . 
     
     
       11. The composite part or structure according to  claim 10  wherein said composite part or structure forms at least part of an aircraft primary structure. 
     
     
       12. A method for making a composite part or structure comprising the step of providing a pre-impregnated composite material according to  claim 1  and curing said pre-impregnated composite material to form said composite part or structure. 
     
     
       13. The method for making a composite part or structure according to  claim 12  wherein said composite part or structure forms at least part of an aircraft primary structure. 
     
     
       14. A method for making a composite part or structure according to  claim 12  wherein said first group of polyamide particles comprises polyamide 11 particles and said second group of particles comprises crosslinked polyamide 12 particles that comprise crosslinked polyamide 12. 
     
     
       15. A method for making a composite part or structure according to  claim 12  wherein said curing agent comprises 4,4′-diaminodiphenyl sulphone. 
     
     
       16. A method for making a composite part or structure according to  claim 12  wherein said reinforcing fibers comprise a plurality of carbon fiber tow which each comprises from 10,000 to 14,000 carbon filaments wherein the weight per length of each of said carbon tows is from 0.2 to 0.6 grams per meter and wherein the tensile strength of each of said carbon tows is from 750 to 860 kilopounds per square inch and the tensile modulus of each of said carbon tows is from 35 to 45 megapounds per square inch. 
     
     
       17. A method for making a pre-impregnated composite material that is curable to form a composite part, said method comprising the steps of:
 A) providing reinforcing fibers comprising carbon fibers; and 
 B) impregnating said reinforcing fibers with an uncured resin matrix wherein said uncured resin matrix comprises:
 a) an epoxy resin component comprising from 17 to 27 weight percent of a hydrocarbon epoxy novolac resin, based on the total weight of said uncured resin matrix, and from 26 to 36 weight percent of a triglycidyl meta-aminophenol, based on the total weight of said uncured resin matrix; 
 b) 11 to 19 weight percent of a thermoplastic particle component based on the total weight of said uncured resin matrix, said thermoplastic particle component comprises a mixture of a first group of polyamide particles that do not comprise crosslinked polyamide and a second group of polyamide particles that comprise crosslinked polyamide; 
 c) 7 to 12 weight percent of a thermoplastic toughening agent, based on the total weight of said uncured resin matrix, said thermoplastic toughening agent comprising polyethersulfone; and 
 d) 17 to 27 weight percent of a curing agent, based on the total weight of said uncured resin matrix, said curing agent comprising 4,4′-diaminodiphenyl sulphone and/or 3,3′-diaminodiphenyl sulphone. 
 
 
     
     
       18. The method for making a pre-impregnated composite material according to  claim 17  wherein said first group of polyamide particles comprises polyamide 11 particles and said second group of particles comprises crosslinked polyamide 12 particles that comprise crosslinked polyamide 12. 
     
     
       19. The method for making a pre-impregnated composite material that is curable to form a composite part according to  claim 17  wherein said curing agent comprises 4,4′-diaminodiphenyl sulphone. 
     
     
       20. The method for making a pre-impregnated composite material that is curable to form a composite part according to  claim 17  wherein said reinforcing fibers comprise a plurality of carbon fiber tow which each comprises from 10,000 to 14,000 carbon filaments wherein the weight per length of each of said carbon tows is from 0.2 to 0.6 grams per meter and wherein the tensile strength of each of said carbon tows is from 750 to 860 kilopounds per square inch and the tensile modulus of each of said carbon tows is from 35 to 45 megapounds per square inch.